The European infectious diseases agency is to recommend that member states prepare strategies for possible vaccination programs to counter rising cases of monkeypox, amid growing evidence of community transmission of the disease.

The European Center for Disease Prevention and Control (ECDC) said on Sunday in response to questions that it would make the recommendation in a risk assessment to be published on Monday. Any vaccination campaign would use the existing smallpox vaccine as there is no approved monkeypox inoculation and would mean immunizing close contacts of confirmed monkeypox patients.

Smallpox immunity has been shown to provide some cross-protection against monkeypox. Smallpox was declared eradicated in 1980, but vaccine stocks were maintained to guard against a possible resurgence.

The Stockholm-based ECDC noted that it was “not an easy decision” to recommend smallpox vaccination of close contacts with monkeypox at this stage and said a risk-benefit analysis for each affected individual should be company. The vaccine available in the EU, Imvanex from Danish drugmaker Bavarian Nordic, is not licensed for use against monkeypox and there are no safety data on its use in immunocompromised people or in young children, those most at risk of the disease, the ECDC said. .

The approach, known as post-exposure prophylaxis, is recommended because the disease is spreading among people with no known link to another confirmed case or affected region, in what is known as community transmission.

The arm and torso of a patient with monkeypox skin lesions. Incubation can take up to 21 days © Brian Mahy/CDC/Handout/Reuters

The vaccine is also available in the UK, where health authorities have recommended a similar strategy.

Scientists and health authorities are struggling to better understand the outbreak, the largest to date outside areas where it is endemic. As of Saturday, 92 lab-confirmed cases had been reported to WHO in 12 countries where the virus does not normally circulate.

Israel, Austria and Switzerland said they confirmed their first cases on Sunday.

Monkeypox is a viral disease and most, but not all, cases so far have been seen in men who have sex with men. According to the ECDC, human-to-human transmission occurs primarily through large respiratory droplets. Since these droplets do not travel far, prolonged contact is required. The virus can also be transmitted through other bodily fluids. Health authorities seek to rule out aerosol transmission or the evolution of the virus to a more easily transmissible strain.

The World Health Organization said over the weekend that available information suggested transmission “is occurring among people in close physical contact with symptomatic cases”. All lab-confirmed specimens to date have been confirmed to belong to the West African subfamily. No associated deaths have been reported so far.

Symptoms are flu-like and also include a rash, which often starts on the face and then spreads to other parts of the body. Incubation can last up to 21 days, complicating contact tracing efforts.

“The situation is changing and WHO expects there will be more cases of monkeypox identified as surveillance expands in non-endemic countries,” the Geneva-based health body added.

Shares of Bavarian Nordic, the maker of the smallpox vaccine, have risen about 55% since May 19, when the number of European cases began to rise. A European health official said “thousands” of doses of Imvanex were readily available.

Bavarian Nordic did not immediately respond to a request for comment on Sunday.

Meanwhile, US President Joe Biden said on Sunday that the outbreak “is something everyone should be concerned about.” Speaking from South Korea, where he was on an official visit, he said the United States was in the process of identifying a suitable vaccine to counter the virus.

Ashish Jha, the White House coronavirus response coordinator, told ABC on Sunday that the United States has identified one case in Massachusetts and one in New York and is tracking others. But he said it was “a virus we understand” and that there were vaccines and treatments to fight it.

Additional reporting by James Shotter in Jerusalem